Hybrid electric vehicles selectively use an internal combustion engine as a source of input torque to a transmission, alone or in conjunction with the traction motor(s), while extended-range electric vehicles use a smaller engine only when needed, and solely to power an electric generator. Battery electric vehicles forego use of the small gas engine, and instead operate using stored electrical energy or regenerative braking energy. All three vehicle configurations can operate solely on electricity in what is referred to as an electric vehicle (EV) mode.
In some of the above vehicle embodiments, a Rechargeable Energy Storage System (RESS) is used to alternatively store and deliver the substantial amounts of electrical energy needed for driving the traction motor(s). The RESS may consist of a battery pack having multiple battery modules each containing multiple cylindrical or flat/tabular battery cells.
It is desired to employ vapor compression systems within the above vehicle embodiments that may operate efficiently, while allowing for extended electric range operation at a variety of ambient temperatures.